Resolving scales of aquifer heterogeneity using ground penetrating radar and borehole geophysical logging |
| |
Authors: | S A Q McArthur D M Allen R D Luzitano |
| |
Institution: | (1) Department of Earth Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada;(2) Golder Associates Ltd, #500-4260 Still Creek Drive, Burnaby, BC, V5C 6C6, Canada; |
| |
Abstract: | Accurate and reliable characterization of aquifer heterogeneity remains one of the foremost problems in hydrogeology. In this
study, ground penetrating radar (GPR) and borehole geophysical logging are used to investigate scales of heterogeneity present
locally (<500 m laterally) within an outwash deposit comprised of inter-bedded and cross-bedded sands and gravels of glaciofluvial
origin. At a small scale (<15 m laterally), gamma log data in adjacent boreholes show evidence of fining upward sequences,
occasional coarsening upward sequences, and abrupt changes in grain sizes, which appear to be laterally continuous at scales
of 10 m. At the site scale (<500 m laterally), GPR profiles show a strong reflection interpreted as the water table. Reflectors
in the unsaturated zone are more clearly defined than those beneath the water table due to signal attenuation within the saturated
sediments. Undulating to discontinuous reflectors at scales of 10–15 m are interpreted to result from interbedded and cross-bedded
sands and gravels. A few laterally continuous horizontal to sub-horizontal reflectors, which extend at least up to 360 m,
are interpreted as unconformities, based on evidence of gravel bars, truncation of underlying units, as well as scour and
fill features in a nearby gravel pit exposure. Overall, the integration of these two geophysical methods provided evidence
of unit correlation at the two scales of investigation. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|